The traditional technique for taking dental impressions and forming stone dental models is well known. Briefly, the procedure comprises inserting impression posts into one or more dental implant wells, positioning an impression cap on each impression post, placing impression material around the impression caps (either via injecting the material at the desired locations or positioning an impression tray with impression material around the caps), waiting until the impression material hardens and withdrawing the impression material with the caps embedded therein. The posts remain in the implant wells and are then removed individually. A dental analog is then inserted into each impression cap and a stone model is formed around the dental analogs.
A number of drawbacks are associated with the prior art components utilized for taking dental impressions and forming stone dental models. For instance, often the orientation of the dental implants within the mouth of a patient are not vertical, but rather are at non-orthogonal angles. Due to the length of the standard impression post and the angles of adjacent implants, it is often the case that the insertion of impression posts interfere with each other. Furthermore, difficulty is added to the withdrawal process when lifting the impression off of the gums at an essentially orthogonal angle, with caps embedded therein at non-orthogonal angles. In addition to the difficulty, caps may be dislodged or shifted within the impression material during the withdrawal process, resulting in misaligned prosthetics.
U.S. Pat. No. 6,540,515 to Tanaka discloses a magnetic attachment used for retaining a dental prosthesis, comprising a male part which may be fixed to an abutment and a female part which may be fixed to said dental prosthesis. The male part of the magnetic attachment includes a head portion, which may be attached to the female part, and a fixing member used for fixing the male part to said abutment. The female part includes a cap portion having a cover portion for covering the male part.
Magnetic attachment systems have advantages over mechanical attachment systems in that excessive stress on the implants at the time of the removal of the dental impression are reduced, as is the difficulty involved in the withdrawal process.
However, prior art magnetic attachment systems and methods, while provide a benefit when used for taking dental impressions, have drawbacks when forming a stone model around dental analogs. That is, when forming a stone model the analog is often easily moved due to its length and the moments generated by the force applied on it, thereby decreasing the accuracy of the replica.